1. Technical Field
The present invention relates to an illumination device suitable for an image processing device and a method for producing the illumination device.
2. Related Art
Conventionally, various image processing techniques are used in the field of FA (Factory Automation). For example, a visual sensor device disclosed in Japanese Unexamined Patent Publication No. 10-320538 is an inspection device that is aimed at wide range of objects from a small object such as an electronic component to a large object such as an automobile. In such visual sensors, the object is imaged to obtain image data and a determination whether the object is non-defective or defective is made by performing image recognition processing to the image data.
Japanese Unexamined Patent Publication No. 10-320538 discloses a configuration in which a camera used to obtain an image of the object and a light source used to illuminate the object during the imaging are integrated.
Recently, an illumination device in which a light emitting element such as an LED (Light Emitting Diode) whose power consumption is less than ever before is used is rapidly developed because of an environmental problem. The LED is used as a light source even in the visual sensor disclosed in Japanese Unexamined Patent Publication No. 10-320538. For example, the following conventional techniques are used as the illumination device in which the LED is used.
In a light irradiation device disclosed in Japanese Unexamined Patent Publication No. 2006-179387, plural LEDs are disposed such that each optical axis has a predetermined oblique angle with respect to an axis line direction of a ring-shaped main body, the LEDs located on the same circumference have the same directivity in the plural LEDs, at least one pair of adjacent LEDs located on the same circumference have a different directivity, which allows lighting to be switched in each plural LED located on the same circumference. Therefore, a light irradiation range can be adjusted.
Additionally, in the light irradiation device disclosed in Japanese Unexamined Patent Publication No. 2006-179387, part of a flexible wiring board is cut out, and a cut-out piece is joined to form a cut-head conical concave surface, which allows an irradiation angle to be adjusted.
An LED illumination device disclosed in Japanese Unexamined Patent Publication No. 2009-054293 includes plural LEDs with which an object is illuminated, a board on which the LEDs are mounted, and a driving mechanism that drives the board to change optical axis directions of the LEDs. Therefore, brightness of the illumination is stabilized without increasing the number of LEDs.
In a ring type illumination device disclosed in Japanese Unexamined Patent Publication No. 2008-139708, plural LED rows are concentrically provided, plural optical members are concentrically provided according to each LED row such that illumination modes with the LED rows with respect to a workpiece differ from each other, and optical members are continuously integrated. Therefore, one ring type illumination device can respond to plural kinds of objective lenses and workpieces.
In an LED illumination device disclosed in Japanese Unexamined Patent Publication No. 2009-146841, a base portion includes plural projections that are projected upward from an upper surface, plural LEDs are mounted on an upper surface of an LED board, through-holes are made in the LED board as many as the projections such that a leading end of the projection penetrates through the through-hole, the leading end of the projection penetrates through the corresponding through-hole to position and dispose the LED board on the upper surface side of the base portion, insertion holes are made as many as the projections such that the leading end of the projection penetrating through the through-hole is inserted in the insertion hole, and the leading end of the projection is inserted in the corresponding insertion hole to position and dispose the projection on the upper surface side of the LED board, the LED illumination device including a lens holder that has a reflecting part in which a reflecting surface is formed at each LED, the reflecting surface standing upward from the upper surface of the LED board while surrounding one LED in the vicinity of the upper surface of the LED board.
As described above, because the visual sensor is intended to measure various objects, according to one or more embodiments of the present invention, many variations (product group) are lined up for an illumination visual field and a work distance (hereinafter also referred to as “WD”) such that the light source (that is, illumination) can be applied to any object.
However, in the visual sensor disclosed in Japanese Unexamined Patent Publication No. 10-320538, because the illumination visual field and the WD cannot be adjusted, it is necessary to prepare chassis and the LEDs according to the number of variations, which results in cost increase.
In the light irradiation device disclosed in Japanese Unexamined Patent Publication No. 2006-179387, it is necessary to prepare the flexible wiring boards according to the number of variations, which results in cost increase. It is also necessary to obliquely dispose each LED with respect to the irradiation direction of the light irradiation device, which results in an angle being relatively hardly set and adjusted in order to realize the desired illumination visual field and WD.
In the configuration of the LED illumination device disclosed in Japanese Unexamined Patent Publication No. 2009-054293, because the illumination visual field and the WD are mechanically adjusted, a structure is relatively complicated, which results in cost increase.
In the ring type illumination device disclosed in Japanese Unexamined Patent Publication No. 2008-139708, it is necessary to prepare annular lenticular lenses according to the number of variations, which results in cost increase.
In the LED illumination device disclosed in Japanese Unexamined Patent Publication No. 2009-146841, it is necessary to prepare the base portions including the plural projections, designed according to the illumination visual fields and WDs, according to the number of variations, which results in cost increase. Additionally a position deviation cannot be corrected when the board is mounted on the LED because the plural lenses are retained in one lens holder, which results in a relatively positional accuracy between the LED and the lens being degraded.